1. Field of the Art
This invention relates to a pattern measurement method, and more particularly to a pattern measurement method for measuring a taper angle, a thickness or a depth of a semiconductor integrated circuit pattern.
2. Prior Art
In the manufacturing process of semiconductor integrated circuits, there occurs a need to measure a taper angle, a thickness or a depth for various patterns formed on the semiconductor substrate. Ordinarily known conventional methods for measuring such a fine pattern are as follows.
(1) Method of cleaving a sample to observe its cross section by a scanning electron microscope.
(2) Method of vacuum-depositing gold onto a sample to irradiate an electron beam thereto to use a scanning electron microscope provided with a pair of electron detectors arranged symmetrically with respect to the electron beam, thus to conduct a signal processing, e.g., calculation of sum of signals obtained by a pair of detectors and difference therebetween, etc.
(3) Method of using the principle of a stereoscopy widely used in the field of remote sensing to apply image processing to secondary electron images observed from two different directions to implement a processing such that both images match with each other, thereafter to make a measurement using a geometrical relational equation.